Struct BaseRefreshDriver 

pub(crate) struct BaseRefreshDriver {
    waiting_for_frame: Arc<AtomicBool>,
    event_loop_waker: Box<dyn EventLoopWaker>,
    observers: RefCell<Vec<Rc<dyn RefreshDriverObserver>>>,
    refresh_driver: Rc<dyn RefreshDriver>,
}

The BaseRefreshDriver is a “base class” for RefreshDriver trait implementations. It encapsulates shared behavior so that it does not have to be implemented by all trait implementations. It is responsible for providing RefreshDriver implementations with a callback that is used to wake up the event loop and trigger frame readiness.

Fields

waiting_for_frame: Arc<AtomicBool>

Whether or not the BaseRefreshDriver is waiting for a frame. Once the RefreshDriver informs the base that a frame start happened, this becomes false.

event_loop_waker: Box<dyn EventLoopWaker>

An [EventLooperWaker] which alerts the main UI event loop when a frame start occurs.

observers: RefCell<Vec<Rc<dyn RefreshDriverObserver>>>

A list of internal observers that watch for frame starts.

refresh_driver: Rc<dyn RefreshDriver>

The implementation of the RefreshDriver. By default this is a simple timer, but the embedder can install a custom driver, such as one that is run via the hardware vsync signal.

Implementations

impl BaseRefreshDriver

pub(crate) fn new( event_loop_waker: Box<dyn EventLoopWaker>, refresh_driver: Option<Rc<dyn RefreshDriver>>, timer_refresh_driver: &LazyCell<Rc<TimerRefreshDriver>>, ) -> Self

pub(crate) fn add_observer(&self, observer: Rc<dyn RefreshDriverObserver>)

pub(crate) fn notify_will_paint(&self, painter: &mut Painter) -> bool

Notify the observers that a frame is about to be painted. Returns whether they were notified, which they are not while waiting for the next frame to start. When they are not notified, it is the caller’s responsibility to ensure that a paint happens once the next frame starts, so that the observers are notified then.

fn observe_next_frame(&self)

pub(crate) fn wait_to_paint(&self) -> bool

Whether or not the renderer should trigger a message to the embedder to request a repaint. This might be true if we are animating and we are still waiting for a new frame from the RefreshDriver.